Production of moldable compositions



UNITED STATES PA EN D PRODUCTION OF Momma; COMPOSITIONS rm. Pollak, Vienna, was

No Drawing. Application July 7, 1931, Serial No. 152,420. In Austria May a, 193':

2 Claims. (Cl. 260-439) This invention relates to the production of ar-' tificial compositions, and more particularly of mol'iing powders destined to be made up into molded articles either by the hot pressing or by may be caused to precipitate out various additions may be made to this solution either at the beginning or in the course of the condensation process, provided these added substances are capable of being precipitated out again. After the carrying out of the precipitation reactioni'n the aqueous solution of the soft resin it becomes possible out of the thus purified soft resin to co nvert the insoluble hard resin directly into the dethe use of considerable uantities of filler, they fuse to very thin liquids-when heated. They pass readily through the thinnest injection tubes, and yet set particularly rapidly to infusible molded shapes. These compositions are thus emi- 5 the hot injecting (die casting) method. The prosired molding powder, with the aid of. acid, for- 5 duction of the molding powder according to the maldehyde, and a suitable flux. invention is effected in two stages, the first of It is advisable to treat the aqueous solution which comprises-condensing an aqueous solution of soft resin for example with such bodies of of urea and hexamethylenetetramine in the abbasic reaction as form carbonates that are inl0 sence of formaldehyde by a protracted boiling soluble in'water, such as for instance oxides and process, while in the second stage the reaction hydroxides of the biand trivalent metals. In mass resulting from the first stage is converted order to bring about complete precipitation of with formaldehyde and a flux. the'insoluble precipitates it is desirable to dilute I have found that substances contained in the the solution sufliciently with water;

aqueous solution of the soft resin may be precipi- The carbonates present may also be removed 16 tated out without the condensation mass itself from the solution by boiling the solution with a going into precipitation. This is the case since suitable acid until the carbon dioxide has esthe aqueous solution contains, besides the soft caped, and then eliminating the amines combined resin, other compounds as well, such as amines, with the acid, as insoluble complex salts or in a s 20 and ammonium compounds, ammonium carbosimilar manner. The substances added as con- 20 nate, and the like, and also the substances added densing agents, provided they are capable of at the commencement or in the course of the conforming insoluble compounds, may also be redensation process, which do not react with the moved from the solution before'the hardening condensation mass. The quantities of amines process, This has the advantage that the and carbonates present in the solution of the soft amounts of. these additions may be regulated at 25 resin may be quite remarkable. They arise from will, without .the necesity for considering whether the decomposition of hexamethylenetetramine the same could have any deleterious effect in the insofar as the latter does not participate in the further course of the hardening process or not. condensation process, (cf. Berliner Berichte, Vol. Thus the substances added and the quantities IQXVIH, 1905, pp. 880 if). Whereas hitherto, thereof used, for the purpose of accelerating or v30 on account of the presence of all these substances facilitating 'the condensation process, may be in the solution of the soft resin, it has been necesdetermined without regard for what effect the sary first to convert the soluble soft resin, by a same might have upon the subsequent course of baking process of long duration, into asoluble the reaction. By using appropriately large quanhard resin, with the view of thereafter hardening titles of such additions it becomes possible so to 35 this soluble hard resin with the aid of formaldecurtail or to control the condensation process hyde I have succeeded in making the surprising that more highly or less highly polymerized proddiscovery that by precipitating out substances ucts are obtained in the same periods of time. contained in the soluble soft resin not only can To produce suitable hot molding powders it 40 the abovementioned and fairly troublesome bakis necessary in this case also to add certain fluxes 40 ing process be dispensed with, but that in this to the mass, such as for example reaction prodmanner there can be obtained particularly high ucts from thiourea or its mono-substitution quality molding powders which have remarkable products, and formaldehyde, as also the confiowing properties, and which harden more rapiddensation products from urethane and. formaldely than any powders of this kind hitherto known. hyde, and phenol and formaldehyde. What is 45 For this reason the molding powders according essential is that these fluxes shall become conto this invention are particularly well suited for verted into hardened resins in the hot press and handling by the die casting method. at the same time serve as solvent for the urea In consequence of the readiness with which subresins. The compositions obtained in this manstances contained in the solution of the soft resin ner are remarkable for the fact that, in spite of 50 nently well suited for the hot die casting or hot injecting method of molding.

The following are illustrating examples of the practical carrying out of the method according to the present invention.

Examples (1) 240 parts by weight of urea are heated with 130.67 parts by weight of hexamethylenetetramine, 200 parts by volume of water, and one part by weight of phosphoric acid, for 20 hours under reflux. To the solution of the resulting soft resin there are then added 5 parts by weight of burned magnesia, and the resulting mixture is thereafter diluted with 700 parts by volume of water, filtered hot from the precipitated out ammonium-magnesium-phosphate, and evaporated down as required. There is then added a solution of 101 parts by weight of thiourea in 500 parts by volume of 40% formaldehyde, after which the resulting mixture is neutralized, mixed with a suitable filler (e. g. cellulose) with the addition of suitable coloring matter, dried at a temperature of -100 C., and pulverized. In this manner there is obtained a hot molding powder which has excellent flowing properties, sets very rapidly, and yields molded articles that are fast to boiling. When used with the hot injecting method perfect shapes are obtained within a few seconds at each operation.

(2) A particularly pure product is obtained if the condensation solution produced in accordance with Example (1) is acidulated with phosphoric acid (16 parts by weight) until the solution is of permanently acid reaction, the acid solution boiled for a short time to destroy the carbonates, and only then rendered alkaline again with magnesia (24 parts by wt.), allowing the ammonium-magnesium-phosphate to become precipitated out of the solution.

(3) Itammonium sulphate is utilized as condensing agent in this method it is advantageous to add barium hydroxide or caustic lime to the solution'after condensation. Thus for example if the solution given in Example (1) be condensed with 2 parts by weight of ammonium sulphate instead of with phosphoric acid there is afterwards employed an addition of 12 parts by weight of barium hydroxide for precipitating out the sulphate and the carbonate. This solution is then boiled for half an hour. The dissolved excess of the alkaline earth is then precipitated with the accurately calculated required quantity of an acid that yields insoluble salts with the base used, for example sulphuric acid, oxalic acid, phosphoric acid. The filtrate obtained gives the same molding powder as that described in Example '(1-).

I claim:

1. In a process for making condensation products by interacting urea andhexamethylenetetramine in aqueous solution in the absence of formaldehyde, in the presence of slight quantitles of a catalyst and with heating for a prolonged period of time, said condensation products being capable of being worked up to molding powders by means of formaldehyde and a flux, the step of carrying out the interaction of the said constituents in the presence of a slight quantity of a catalyst selected from the group; of acids and salts thereof, the acid radical of which yields water-insoluble salts, and of precipitating and filtering out from the said aqueous solution the catalyst and impurities present therein with the aid of reagents selected from the group consisting of the oxides and hydroxides of the biand trivalent metals forming water-insoluble salts the said acids and salts thereof.

2. In a. process for making condensation products by interacting urea and hexamethylenetetramine in aqueous solution in the absence of formaldehyde, in the presence of slight quantities of a catalyst and with heating for a prolonged period of time, said condensation products being .capable of being worked up to molding powders by means of formaldehyde and a flux, the step of carrying out the interaction of the said constituents in the presence of a slight quantity of. a catalyst selected from the group of acids and salts thereof, the acid radical of which yields water insoluble salts, of adding acid to expel carbon dioxide evolved during the condensation process from the said solution, and of precipitat ing and filtering out from the said aqueous solution the added substances'and impurities present therein with the aid of reagents selected from the group consisting of the oxides and hydroxides of the biand trivalent metals forming water-insoluble salts with the impurities and the said acid radical of the said acids and salts thereof.

FRITZ POLLAK.

. with the impurities and the said acid radicals of 

